Owners rarely went on voyages, so the captain was in command and his employment relied upon the profits returned.
Profits depended on how many slaves were delivered and on how low the costs could be kept. This had direct consequences for the terrible conditions the enslaved Africans were placed in.
Slaves were shackled and closely packed in a ship's hold. The ships were adjusted to maximise the number of slaves that could be taken on board.
The height between decks where the slaves were kept was 1.73m (5 ft 8 inches), but the shelves where they lay often measured less than 0.45m (1ft 6in) in height. Male slaves were usually shackled together at the foot.
In theory, each man was allotted a space of 1.8m (6ft) by 0.4m (1ft 4in). Whether they were tight packed or loose packed appears to have been dictated by how much profit could be made rather than any humanitarian concern.The argument was a matter of simple maths.
Tight-packing meant more slaves were carried on board for little more cost. These gains could be measured against losses: the slave death rate was higher and weaker slaves were less resistant to disease.